Generally, variable transmittance light filters, such as electrochromic light filters, can be used in architectural windows, skylights, and in windows, sunroofs, and rearview mirrors for automobiles. Such variable transmittance light filters typically reduce the transmittance of direct or reflected sunlight during daytime through the window, while not reducing such transmittance during nighttime. Not only do such light filters reduce bothersome glare and ambient brightness, but they can also reduce fading and generated heat caused by the transmission of sunlight through the window.
Variable transmission windows generally have not been widely accepted commercially for several reasons. First, they tend to be very expensive due to the cost of materials required for their construction, and their complex construction can make mass-production difficult. Additionally, variable transmission windows tend to have a lower life expectancy than conventional windows due to degradation of some types of variable transmittance materials used in the windows. The combination of added cost and lower life expectancy has generally deterred many architects, designers, and builders from using variable transmission windows.
Generally, variable transmission windows have also not been widely accepted commercially in vehicles designed for the transportation of passengers, such as, for example, busses, airplanes, trains, ships, and automobiles. Exemplary challenges for providing variable transmission windows in such applications are, but not limited to, providing effective, coordinated, individual and central control of multiple variable transmission windows, providing multiple modes of operation responsive to individual or collective passenger needs, providing the ability to quickly change window transmittance states, minimizing system power consumption, protecting against environmental factors such as moisture and power surges, protecting windows from excessive heat and physical external loads, and providing user interfaces allowing relatively unsophisticated users to understand and control the windows. Additionally, challenges can generally be a barrier to providing system features needed to address the above-identified needs.